Method of applying noxious cleaning chemicals



United States Patent 3,518,119 METHOD OF APPLYING NOXIOUS CLEANINGCHEMICALS Robert Emanuel Farison, Cincinnati, Ohio, assignor to W. R.Grace & (30., a corporation of Connecticut No Drawing. Continuation ofapplication Ser. No. 595,051, Nov. 17, 1966. This application Sept. 4,1969, Ser. No. 855,385

Int. Cl. B08b 3/08 U.S. Cl. 134-36 I r 2 Claims ABSTRACT OF THEDISCLOSURE Process for applying noxious cleaning chemicals to opensurfaces without the formation of mist or overspray, eliminating theusual hazards to. operating personnel when the noxious compositions areused, employing a foamable cleaning composition mixed with at least .90volume percent gas.

This application for United States Letters Patent is a continuation ofapplication, Ser. No. 595,051, filed Nov. 17, 1966.

The process of this invention is a method for cleaning open surfaceswith noxious cleaning compositions containing eye, nose, or skinirritants comprising applying an aqueous foam containing the noxiouscleaning composition to the open surface to be cleaned, and rinsing thefoam from the surface with water.

Spray cleaning of open surfaces such as exteriors of trucks, tractortrailers, aircraft, and the interiors of factories, storage tanksandother open areas is Widely used because less labor is required to applythe cleaning liquids to the 'open surfaces. In general, relatively mildcleaning compositions are used in these spray cleaning operations. Manyof the most active cleaning compositions, however, contain strongchemicals such as strong acids or bases, volatile irritants, or otherchemicals which cannot be used in spray cleaning open surfaces becausethey are hazardous to operating personnel." These strong noxiouschemicals, through distillation, mist, or overspray offer potentialdanger to the eyes, nose, and skin of the operating personnel.

It is the object of this invention to provide a process for cleaningopen surfaces with cleaning compositions containing noxious chemicalswhich is not subject to the above hazards. This object is obtained byapplying the strong cleaning compositions to the open surfaces as astable foam, eliminating misting, over-spray, and irritating vapors, andreducing the chance of irritating contact with personnel.

Foam cleaning is effected by pumping high foam cleaning solutions in amechanical system in which compressed gases non-reactive with thecleaning chemicals, such as air, are mixed with the cleaning solution toproduce a stable, copious foam. This dry foam clings to the surfaces tobe cleaned, increases the contact time of the liquid with the surfaces,prevents rapid drying and runoff of the liquid cleaner, splashing,over-spray, misting, and distillation of irritating vapors of the liquidsolutions into the air.

Foam cleaning has been previously disclosed for cleaning closed vesselswith foams containing strong acids to eliminate scale from the vesselwalls in Brenner et al. U.S. Pat. 3,037,887, the disclosure of which isincorporated herein by reference for background information. In theprocess of Brenner et al., the vessel to be treated was filled with foamcontaining a strong acid and other chemicals, and further foam waspassed through the closed vessel until the vessel walls had beendescaled.

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In the closed vessel, no hazards to operating personnel were present,and the foam was employed to decrease the volume of cleaning solutionrequired since it was necessary to entirely fill the closed vessel withthe cleaning solution to effect descaling.

The process of this invention is a method for cleaning exposed surfacesby spraying foamed cleaning compositions on the open surfaces. Anymethod for mixing gas with the cleaning solution to form a stable foamcan be employed. Application Ser. No. 534,378 filed Mar. 15, 1966, nowU.S. Pat. No. 3,337,195 discloses a suitable foam generating apparatuswhich feeds compressed air and the foamable liquid to a gas-liquidmixing means where the gas and liquid is mixed to form a foam, anddischarges the foam through an outlet conduit. Another suitable deviceis shown in Pat. No. 1,141,243. A variety of systems are summarized inPat. No. 2,916,855.

The method of applying the foam to the surface being cleaned is notcritical, but spray application is preferred.

The process of this invention is suitable for applying a foam formedfrom a foamable cleaning composition containing irritatingconcentrations of noxious or hazardous chemicals. Since the irritatingaspects of spraying liquids containing these noxious components isavoided, more concentrated and active cleaning compositions can be usedto clean open surfaces.

Suitable concentrated foamable cleaning compositions containinghazardous chemicals which are suitable for cleaning open surfaces aredisclosed in application Ser. No. 540,212 filed Apr. 5, 1966. Theparticular foamable compositions used in the process of this inventionare not critical, but the compositions must be capable of forming astable foam when mixed with air. In the concentrations applied to thesoiled surface, a foam of the compositions containing volume percent airshould retain 25 percent of its volume and preferably at least 50percent of its volume 10 minutes after being applied to the surface.

The method of this invention is particularly suitable for applyingcleaning compositions containing mineral acids such as sulfuric andhydrochloric acids, sulfamic acid, or containing alkaline irritants suchas caustic soda, potash, and highly basic amines.

The cleaning foamable composition is mixed with sufficient gas toprovide a foam containing at least 90 volume percent and preferably lessthan 97 volume percent gas. Any suitable gas which is non-reactive withthe components of the cleaning composition can be used. Examples ofsuitable gases include nitrogen, carbon dioxide, air, and halogenatedhydrocarbon gases.

After the cleaning foam is applied to the soiled surface and when thecleaning action is complete, the residual foam and cleaning compositioncan be rinsed from the surface, preferably with a water wash. The rinsecan contain neutralizing chemicals, defoaming compounds, andconventional rinse surfactants to promote the rinsing action and preventdeposit of residue on the cleaned surfaces.

The invention will be further illustrated by the following specific butnon-limiting examples.

EXAMPLE I' A foaming assistant containing, in parts by weight asdescribed in Ser. No. 540,212 filed Apr. 5, 1966, 21 parts water, 31parts of sodium salt of dodecyl benzene sulfonic acid, 33 parts of asodium salt of sulfonated oleic acid, and 15 parts of an ethylene oxidecondensate of coconut fatty acid monoethanolamide containing an averageof about 5 ethoxy groups (CHO) per mole is prepared.

A cleaning solution containing 05 pound per gallon of an industrialcleaner containing, by weight, 70 parts caustic soda, 14 sodiummetasilicate, parts sodium 4 tripolyphosphate, 5 parts tetra sodiumpyrophosphate, and 4 parts soda ash is prepared. One gallon of an 80weight percent solution of thefoaming assistant is added per 50 gallonsof the cleaning solution. 4

The foamable cleaning composition is then mixed with 9097 volume percentair in thefoaming device described in application Ser. No. 534,378 filedMar. 15, 1966, and the foam is applied to a soiled surface. Afterminutes, the remaining foam, dirt, and residual cleaning agent is rinsedfrom the surface.

At no time during the application of the foam cleaning composition tothe surface being cleaned isthe operating personnel contacted withmists, sprays, or vapors of the highly alkaline cleaner.

EXAMPLE II The procedure of Example I is followed with the three Onegallon of the foaming assistant described in Example I I per 50 gallonsof solution.

('B) A solution containing about 0.25 pound per gallon of a causticcleaning composition comprising, by weight, 60 parts chlorinatedtrisodium phosphate, 23 parts soda ash, and 17 parts sodiumtripolyphosphate is mixed with 0.25 gallon of the foaming assistantdescribed in Example I per 50 gallons of solution.

(C) A solution containing about 0.5 pound per gallon of an acid cleaningcomposition comprising about 90 parts by weight sulfamic acid is mixedwith 5 gallons of the foaming assistant described in Example I per 50gallons of solution.

When the foamed cleaning compounds are applied to the surface beingcleaned, splash-back, misting, and irri tating vapors and mists are notevident, even though each of the compounds contains hazardous chemicals.

Obviously, many modifications and variations of the invention ashereinabove set forth can be made without departing from the essence andscope thereof, and only such limitations should be applied as areindicated in the claims.

What is claimed is:

1. A process for cleaning which comprises:

(A) mixin .a fo m bl cleaningv ompos tion, form d (1) a foamingassistant containing 21 parts by weight water, 31 parts by weight of asodium salt of dodecyl benzene sulfonic acid, 33 parts by Weight of asodium salt of-su'lfona'ted oleic acid, and 15 parts by weight of anethylene oxide "condensate of coconut fatty acid monoethan'oL amidecontaining an average of about 5 ethoxy o p (Q p mole, and

(2) a cleaning solutionconsisting of 0.5 pound per gallon of water ofanindust rial cleaner containing parts by weight of caustic soda, 14parts by weight of sodium metasilicate, 5 parts by weight of sodiumtripolyphosphate, 5 parts by'weight of tetra sodium pyrophosphate, and 4parts by Weight of soda ash; 50 gallons of said industrial cleanercombined with one gallon of an weight percent solution of said foamingassistant,

(3) with at least volume percent gas.

(B) applying the foam prepared in step (A) to an open surface to becleaned, said foam characterized as a stable, copious dry foam whichclings to surfaces to be cleaned, prevents rapid drying and runoff ofthe liquid cleaner, without splashing, .overspray, misting anddistillation of irritating vapors of the liquid cleaning solution intothe air; and

(C) rinsing the foam covered surface to remove residual cleaningcomposition.

2. The process of claim 1 wherein the foamable cleaning compositionismixed with less than 97 volume percent gas.

References Cited UNITED STATES PATENTS 1,141,243 6/1915 Foster 134-293,037,887 6/1962 Brenner et al. 134-36 XR 3,078,190 2/1963 Blaser et al13436 XR MORRIS 0. WOLK, Primary Examiner J. T. ZATARGA, AssistantExaminer U.S. Cl. X.R. 1342

